Perfluorocyclicamine, constant boiling composition and process for producing the same

ABSTRACT

A process for producing a perfluorocyclicamine which includes electrolytically fluorinating a triallylamine in anhydrous liquid hydrogen fluoride. A constant boiling composition and process for producing the same is also described.

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application is an application filed under 35 U.S.C. §111(a)claiming benefit pursuant to 35 U.S.C. §119(e)(1) of the filing date ofProvisional Application No. 60/241,741 filed Oct. 20, 2000 pursuant to35 U.S.C. §111(b).

FIELD OF THE INVENTION

[0002] The present invention relates to a novel compoundperfluoro-1-propyl-3,4-dimethylpyrrolidine, a constant boilingcomposition containing the compound, a process for producing thecomposition, and uses of the constant boiling composition.

BACKGROUND OF THE INVENTION

[0003] In the process of manufacturing a semiconductor device, liquidperfluorocarbons (hereinafter referred to as “PFCs”) having an excellentelectric insulating property have been heretofore widely used as theheat medium for controlling the wafer temperature within a chamber in anetching process using a high-voltage plasma or for maintaining a hightemperature or a low temperature in the thermal shock test of a wafer orin the performance inspection of the wafer.

[0004] Recently, a problem of global warming has been raised and basedon the protocol adopted at the Kyoto conference in 1997, Japan has alsostarted to establish goals for reducing the discharge of six kinds ofgases including PFCs and to take a specific action.

[0005] PFCs are very stable (inactive), both thermally and chemically,and are not considered to deplete the ozone layer because the ozonedepleting potential (ODP) thereof is zero due to the absence of chlorineatom in the molecule. Moreover, PFCs are low toxic and noncombustible.By virtue of these excellent properties, they have been widely used,particularly, in the field of manufacture of semiconductor devices wherecorrosion resistance, insulating resistance and the like are required.Representative examples of liquid PFCs include C₅F₁₂, C₆F₁₄ and C₈F₁₈.These PFCs are, however, known to have a great effect on warming becauseof their very high stability and the global warming potential (GWP)thereof are as high as 5,000 to 7,000 (integral term: 100 years,assuming that CO₂ is 1).

[0006] In the case of using these PFCs as the above-described heatmedium in an open system or even in a closed system, since completeenclosure is difficult in view of the apparatus design or structure, thesystem is substantially opened to atmospheric conditions in many cases.Therefore, particularly when the temperature is close to the boilingpoint of the substance used, the substance inevitably volatilizes intothe atmosphere in a large amount. This not only increases the costnecessary for adding and replenishing the heat medium but also raises aserious problem in view of the discharge of a warming gas.

[0007] Hydrofluoroethers (hereinafter referred to as “HFEs”) andhydrofluorocarbons (hereinafter referred to as “HFCs), which areconsidered to have a small effect on warming, have been developed asalternatives of PFCs. A representative example of HFEs is C₄F₉OC₂H₅ anda representative example of HFCs is cyclic C₅H₂F₈. However, thesesubstances are relatively low in boiling point (max.: about 80° C.), andtherefore, they cannot be used at high temperatures which reaches 100°C., and the electric properties thereof are inferior to conventionalPFCs. Because of these reasons, their use in the field of manufacturingof semiconductor devices is limited and these substances are mainly usedas a cleaning agent or a solvent.

[0008] In the process of manufacturing a semiconductor device, the useform of the heat medium is classified into indirect heat transfer anddirect heat transfer. Indirect heat transfer is where the heat mediumitself circulates through a heat transfer path (e.g., heat exchanger)and repeats heat absorption or heat release. Direct heat transfer iswhere the temperature of a material body is changed or maintained whileallowing the heat medium to stand in the state of directly contactingwith the material body, for example, by dipping the material bodydirectly in the heat medium. In either case, a wide temperature regionfrom an extremely low temperature of about −50° C. to a high temperatureof 100° C. must be continuously or intermittently covered. Therefore,there is a demand for a system of operating the transfer of heat by onekind of heat medium. For example, in the case of a substance which doesnot boil in a high temperature region (that is, a substance having ahigh boiling point of at least 100° C. or more), the substance isrequired to have properties of maintaining the liquid phase even in anextremely low temperature region of −50° C., which is included in thetemperature range during use, and required to have appropriate flowingproperties at the same time. For this purpose, the freezing point or thetemperature where the substance starts flowing (pour point) ispreferably lower than the lowest temperature on use.

[0009] In recent years, studies have been made on extremely lowtemperature conditions on the level of −70° C. and therefore, thesubstance must have the required properties at low temperatures. On theother hand, from the standpoint of coping with the warming problem, thesubstance must be reduced in volatilization loss by having the requiredproperties at high temperatures. Accordingly, in practice, the rangefrom the freezing point to the boiling point of the heat medium ispreferably the temperature range ±30° C. during use, namely,approximately from −100 to 130° C. The existing HFEs and HFCs are knownto have a relatively low freezing point but are inferior to PFCs in theelectrical properties such as dielectric breakdown voltage and volumeresistivity. On the other hand, PFCs are excellent in these electricalproperties but those having a low freezing point are liable to have asmall molecular weight and a low boiling point. As such, whenconventional HFEs, HFCs and PFCs are used as a sole compound, theycannot be a preferred heat medium that is well-balanced in physicalproperties by practically having a broad temperature range in terms ofthe temperature range from the freezing point to the boiling point andhaving good electrical properties at the same time.

[0010] Therefore, for example, a method of mixing specific components toprovide an azeotropic composition or an azeotrope-like composition toobtain a constant boiling mixture, or a method of adjusting the mixingratio according to the use conditions to control the properties of themixture may be developed. However, for using the heat medium in such asystem, the constant boiling composition is indispensable, but thecombination of existing HFEs, HFCs and PFCs cannot form an azeotropiccomposition. Moreover, the method of adjusting the mixing ratio highlyprobably incurs changes in the composition and this is disadvantageousin practice.

[0011] The present invention has been made under these circumstances. Anobject of the present invention is to provide a heat medium, which cancontribute to the reduction in the discharge of warming gas by havinghigh boiling properties, can maintain the liquid phase in a widetemperature range during use by having a low freezing point and, at thesame time, is favored with excellent electrical insulating properties.

[0012] As a result of extensive investigations to solve theabove-described problems, the present inventors have found that aconstant boiling composition comprisingperfluoro-1-propyl-3,4-dimethylpyrrolidine,perfluoro-1-propyl-3-methylpiperidine and perfluorotripropylamineexhibits excellent properties as a heat medium in the process ofmanufacturing a semiconductor device. Furthermore, extensiveinvestigations have been made on the process for producing thecomposition. As a result, the present inventors have found that theconstant boiling composition can be easily synthesized by using atriallylamine having high general use property and electrolyticallyfluorinating it in an anhydrous liquid hydrogen fluoride. The presentinvention has been accomplished based on these findings.

SUMMARY OF THE INVENTION

[0013] An embodiment of the present invention (I) is a process forproducing a perfluorocyclicamine, comprising electrolyticallyfluorinating a triallylamine in an anhydrous liquid hydrogen fluoride toproduce a perfluorocyclicamine represented by the following formula (1):

[0014] wherein —X— represents —CF(CF₃)— or —CF₂CF₂—. In a preferredembodiment, the concentration of triallylamine in the anhydrous liquidhydrogen fluoride is in the range from 1 to 20% by mass and the currentdensity is in the range from 0.1 to 10 A/dm².

[0015] Another embodiment of the present invention (II) isperfluoro-1-propyl-3,4-dimethylpyrrolidine which is a novel compound andwhich is a compound represented by the formula (1) where —X— is—CF(CF₃)—.

[0016] Another embodiment of the present invention (III) is a processfor producing a constant boiling composition comprisingcis-perfluoro-1-propyl-3,4-dimethylpyrrolidine,trans-perfluoro-1-propyl-3,4-dimethylpyrrolidine,perfluoro-1-propyl-3-methylpiperidine and perfluorotripropylamine, theprocess comprising electrolytically fluorinating a triallylamine in ananhydrous liquid hydrogen fluoride. In a preferred embodiment, theconcentration of triallylamine in an anhydrous liquid hydrogen fluorideis in the range from 1 to 20% by mass and the current density is in therange from 0.1 to 10 A/dm².

[0017] Another embodiment of the present invention (IV) is a constantboiling composition comprisingcis-perfluoro-1-propyl-3,4-dimethylpyrrolidine,trans-perfluoro-1-propyl-3,4-dimethylpyrrolidine,perfluoro-1-propyl-3-methylpiperidine and perfluorotripropylamine. In apreferred embodiment, the content of perfluorotripropylamine is 55% orless, the boiling point is from 127 to 129° C., and the freezing pointis −100° C. or less.

[0018] Other embodiments of the present inventions (V) and (VI) are anelectrical insulator using the constant boiling composition of theembodiment of the present invention (IV) and a heat medium using theconstant boiling composition of the embodiment of the present invention(IV).

DETAILED DESCRIPTION OF THE INVENTION

[0019] The present invention is described in detail below. With respectto the process for producing perfluoro-tertiary amine, U.S. Pat. Nos.2,519,983 (Simons), 2,567,011 (Simons et al.) and 2,616,927 (Kauck)describe a process of electrolytically fluorinating a triethylamine inan anhydrous liquid hydrogen fluoride to produce aperfluorotriethylamine. Furthermore, L. Conte et al. report in J.Fluorine Chem., 30, 89 (1985) a process of electrolytically fluorinatinga tripropylamine as an alkyl tertiary amine, similarly, in an anhydrousliquid hydrogen fluoride to produce a perfluorotripropylamine(hereinafter referred to as “PFTPA”). As such, the perfluoro-tertiaryamine has been heretofore produced from a corresponding alkyl tertiaryamine.

[0020] With respect to the process for producing a perfluorocyclicamine,E. Hayashi et al. report in J. Fluorine Chem., 26, 417 (1984) that whena pipecoline such as N-(3-chloropropyl)-3-pipecoline is electrolyticallyfluorinated in an anhydrous liquid hydrogen fluoride, a plurality ofperfluoropyrrolidine isomers are present in the electrolyticfluorination product.

[0021] As such, the process for producing a perfluoroalkyl tertiaryamine from a corresponding alkyl tertiary amine by the electrolyticfluorination is known. Also, for obtaining a cyclic amine, a process ofproducing a perfluorocyclicamine starting from a compound having theobjective cyclic structure through electrolytic fluorination is known.However, the process of electrolytically fluorinating a triallylaminewhich is a tertiary amine having an unsaturated alkyl group, to producea perfluorocyclicamine of the present invention is heretofore not knownand is a novel process.

[0022] The present invention has been achieved based on novel knowledgethat a triallylamine which is relatively easily available is used as araw material and as shown in the following formulae (1) and (2), twoallyl groups out of three allyl groups in the molecule are combined aspropyl radicals during the electrolytic fluorination, thereby cyclizingand isomerizing.

[0023] The embodiment of the present invention (I) is a process forproducing cyclic amines, namely,cis-perfluoro-1-propyl-3,4-dimethylpyrrolidine (hereinafter referred toas “cis-PFPDMP”), trans-perfluoro-1-propyl-3,4-dimethylpyrrolidine(hereinafter referred to as “trans-PFPDMP”) andperfluoro-1-propyl-3-methylpiperidine (hereinafter referred to as“PFPMP”), where the cyclic amines are produced by electrolyticallyfluorinating a triallylamine in an anhydrous liquid hydrogen fluoride.For this electrolytic fluorination reaction, a known electrolytic methodheretofore commonly used in the electrolytic fluorination reaction, suchas Simons type electrolytic cell, can be used.

[0024] This reaction is performed in an anhydrous liquid hydrogenfluoride and the concentration of the raw material triallylamine in theanhydrous liquid hydrogen fluoride can be selected from the range of 1to 20% by mass, preferably from 5 to 10% by mass. If the triallylamineconcentration exceeds 20% by mass, the yield is liable to decrease,whereas if it is less than 1% by mass, the reaction is liable to proceedslowly and this is not preferred.

[0025] The current density can be selected from the range of 0.1 to 10A/dm², preferably from 2 to 4 A/dm². If the current density is too high,the electrolytic power excessively increases and side reactions aredisadvantageously liable to take place.

[0026] The electrolytic temperature can be selected from the range of−20 to 50° C., preferably −10 to 20° C. If the reaction temperature istoo low, the electrolytic voltage is liable to excessively increase,whereas if it is too high, hydrogen fluoride is readily volatilized andthis is not preferred.

[0027] The electrolysis reaction can be usually performed under anatmospheric pressure but if desired, may be performed under pressure. Inthe case where the reaction is performed under pressure, the boilingpoint of hydrogen fluoride elevates and cooling of the reaction systemcan be advantageously mitigated.

[0028] In order to perform the electrolytic fluorination with goodefficiency and improve the yield of the objective product, theelectrolytic solution is preferably stirred and mixed during thereaction and for this purpose, means such as mechanical forced stirringor stirring by introduction of an inert gas may be used.

[0029] The thus-obtained perfluorocyclicamine contains, in addition tothe objective product, low molecular substances having a low boilingpoint produced due to the cleavage during the fluorination or polymersubstances produced due to the recombination. The high boiling materialsincluding the objective product have a specific gravity higher than thatof hydrogen fluoride and mostly remain on the inner bottom of theelectrolytic cell. This deposit does not dissolve in the liquid hydrogenfluoride but is separated to form two layers. Therefore, the lower layercan be separated and taken out after the completion of electrolysis.

[0030] The solution of the lower layer separated and discharged iswashed by a known method using an aqueous caustic soda solution or thelike and after neutralizing and removing the hydrogen fluoride, dried toobtain a crude product. From this crude product, at least three kinds ofperfluorocyclicamine isomers can be finally isolated by an isolationmethod using fractional gas chromatography or distillation, preferablyprecision distillation. By performing the structural analysis, eachcomponent can be confirmed to have a structure so that the raw materialtriallylamine is cyclized and thereby isomerized, as described above, toconvert into a perfluorocyclicamine, namely, cis-PFPDMP, trans-PFPDMPand PFPMP. Then, this mixture of components can be separated intorespective components by a precision distillation through increasedplates or a method described later.

[0031] The embodiment of the present invention (II) isperfluoro-1-propyl-3,4-dimethylpyrrolidine (PFPDMP) and can be obtainedby the production process of the present invention (I). This compound isa novel compound and is represented by formula (1):

[0032] where —X— is —CF(CF₃)—. This compound has stereoisomers andincludes cis-3,4-trifluoromethyl form (cis-PFPDMP) andtrans-3,4-trifluoromethyl form (trans-PFPDMP).

[0033] The embodiment of the present invention (III) is a process forproducing a constant boiling composition comprisingcis-perfluoro-1-propyl-3,4-dimethylpyrrolidine (cis-PFPDMP),trans-perfluoro-1-propyl-3,4-dimethylpyrrolidine (trans-PFPDMP),perfluoro-1-propyl-3-methylpiperidine (PFPMP) andperfluorotripropylamine (PFTPA) by the electrolytic fluorinationreaction of a triallylamine.

[0034] The conditions for the electrolytic fluorination may be the sameas the conditions described above with respect to the production ofperfluorocyclicamine. The discharged solution of the lower layerobtained after the electrolysis reaction is washed by a known methodusing an aqueous caustic soda solution or the like and afterneutralizing and removing the hydrogen fluoride, dried to obtain a crudeproduct. The thus-obtained crude product contains PFTPA in addition tothe above-described cis-PFPDMP, trans-PFPDMP and PFPMP. PFTPA is aresultant from the fluorination and conversion of a part of the rawmaterial triallylamine into PFTPA while not allowing the allyl groups tocombine to form a ring. According to the production process of thepresent invention, a mixed composition mainly comprising four kinds ofperfluoro-tertiary amines (including cyclic amine) can be obtained.

[0035] These four kinds of perfluoro-tertiary amines contained in thismixed composition have similar boiling points and, in general,separation into respective single components is difficult in industry.Therefore, in the embodiment of the present invention (IV), the mixedcomposition mainly comprising the above-described four kinds ofperfluoro-tertiary amines is collected as an intermediate fraction, forexample, by a method of cutting unnecessary low boiling and high boilingportions through simple and convenient batch distillation, and themixture is used as it is. The four kinds of perfluoro-tertiary aminesare similar in boiling point and therefore, need not be particularlyseparated into single components. By this process, a mixed compositionhaving a purity of 99% or more (GC area) in terms of the purity of fourcomponents can be obtained. The purity is not particularly limited. Theimpurities contained other than those main components are fundamentallyperfluoro-tertiary amines having a similar cyclic structure and have thesame properties. Therefore, even if these are intermingled in slightamounts, no problem arises. As long as at least the main components arecontained in a concentration of 95% or more, the effect of the presentinvention can be attained. The conditions for the GC analysis may begeneral conditions used in the analysis of fluorine compounds.

[0036] When the boiling point of the mixed composition obtained by theabove-described process is examined while variously changing thecomposition, the boiling point is scarcely changed depending on thecomposition and the mixed composition behaves as a constant boilingcomposition of 127 to 129° C. Accordingly, with respect to the boilingpoint of the mixed composition, the compositional ratio of fourcomponents is not particularly limited. In a preferred embodiment of themixed composition of the present invention (IV), the freezing point is−100° C. or less and the compositional ratio of PFTPA is 55% or less.The compositional ratio of PFTPA can be determined from the GC areapercentage.

[0037] The constant boiling composition of the present invention (IV) isnot limited to the mixed composition obtained by the above-describedproduction process but may be a composition prepared, for example, bymixing cis-PFPDMP, trans-PFPDMP, PFPMP and PFTPA which are separatelyisolated.

[0038] In either case, a constant boiling composition in the vicinity of128° C., that is, an azeotrope-like mixture is fundamentally formed.Since the compositions of the gas phase and the liquid phase are almostthe same at the boiling point, the change in the compositionaccompanying the volatilization during the use can be neglected and thephysical properties are mostly free of fear for changes. Thus, thecomposition is very useful in practice.

[0039] The constant boiling composition of the present invention (IV),which contains perfluorocyclicamines and PFTPA and has a freezing pointof about −100° C. or less and a boiling point of 127 to 129° C.,exhibits in any case a dielectric breakdown voltage of 45 kV or more anda volume resistivity on the order of 10¹⁵ to 10¹⁶. In addition, thecomposition is comparable to conventional heat mediums comprising PFCsand has more excellent characteristics than HFEs. The embodiment of thepresent invention (V) is a use of the constant boiling composition ofthe present invention (IV) as an electrical insulator. This electricalinsulator can be used not only in the field of manufacture ofsemiconductors but also as an alternative of usual insulating oils bysealing it in a transformer, an electric power source breaker, acapacitor or the like.

[0040] The constant boiling composition of the present invention, whichcontains perfluorocyclicamines and PFTPA and has a freezing point ofabout −100° C. or less and a boiling point of 127 to 129° C., maintainsthe liquid phase in the temperature range during use of −70 to 100° C.,for example, under an atmospheric pressure. Accordingly, the embodimentof the present invention (VI) is a use of the constant boilingcomposition of the present invention (IV) as a heat medium. The role ofthis heat medium is not limited only to circulate by itself through aheat transfer path and to indirectly heat or cool a material to whichthe heat is transmitted, but also includes directly contacting amaterial to which the heat is transmitted and heating or cooling thematerial. Furthermore, the temperature range during use is not limitedto the range from −70 to 100° C., and the heat medium may be used underhigher temperature conditions by completely closing the system andmaintaining the liquid state under pressure of atmospheric pressure ormore.

EXAMPLES

[0041] The present invention is described in greater detail below byreferring to the Examples and Comparative Examples, however, the presentinvention should not be construed as being limited thereto. Unlessindicated otherwise herein, all parts, percents, ratios and the like areby weight.

Example 1

[0042] A carbon steel-made Simons type electrolytic cell having aninternal volume of 2 L with an internal cooling coil and an externalcooling jacket was used. The electrode was formed by alternatelyarranging two sheets of anodes and three sheets of cathodes at ananode-cathode distance of 2 mm. The anodes and the cathodes each wasmade of nickel plate having a thickness of about 1.5 mm and theelectrode had an effective anode area of 3.15 dm². The cover of theelectrolytic cell was connected with a reflux capacitor communicatingwith a sodium fluoride tower and the cell was always cooled to −50 to−40° C. Also, in the electrolytic cell, a supply port for liquidhydrogen fluoride and a temperature detecting sensor were provided. Thebottom part of the electrolytic cell was connected with an extractionport and subsequently thereto, a liquid-liquid separator with aninspection hole.

[0043] About 1,270 g of anhydrous liquid hydrogen fluoride wasintroduced into the electrolytic cell and preliminarily electrolyzed,and thereby purified. In this anhydrous liquid hydrogen fluoride, about115 g of raw material triallylamine having a purity of 99% was dissolvedto a triallylamine concentration of about 8% by mass. Through thiselectrolytic solution, a constant current of 9.5 A was passed at acurrent density of 3 A/dm² for 117 hours under an atmospheric pressureto electrolyze the electrolytic solution. During this, the electrolyticvoltage was from 5.9 to 6.7 V. The total quantity of current passed was1,111 A·hr.

[0044] The temperature of the electrolytic solution was kept at 15 to20° C. by means of the reflux condenser and water cooling from the innerand outer sides. The hydrogen fluoride gas accompanying the low boilinggas generated as a by-product was prevented from flowing out and thehydrogen fluoride partly flown out was removed through the sodiumfluoride tower. During the electrolysis, the anhydrous liquid hydrogenfluoride needed was periodically supplied from the supply port.

[0045] After the completion of electrolysis, the high boiling liquid wasextracted from the bottom of the electrolytic cell and the anhydrousliquid hydrogen fluoride was separated and removed through theliquid-liquid separator. The obtained high boiling liquid wasneutralized by a mixed solution of potassium hydroxide and ethanol,washed with water and then dried over silica gel to obtain 381.4 g of acrude product. This crude product was fractionated through a packedcolumn system batch distillation unit and impurities of low boilingsubstance and high boiling substance were removed to obtain 142 g of theobjective substance in a yield of 35% (based on the triallylaminecharged). The low boiling substance removed was mainly aperfluoro-compound having from 4 to 8 carbon atoms and the high boilingsubstance was mainly a triallylamine partially fluorine compound having9 or more carbon atoms or a high polymer.

[0046] The thus-obtained objective substance was analyzed by gaschromatography (carrier gas: He, column: fused silica, 30 m). As aresult, it was confirmed that the objective substance was a mixedcomposition comprising four kinds of main components and the total ofrespective component compositions (GC area standard) was 99% or more.

[0047] This mixed composition was introduced into a precisiondistillation unit (theoretical plate number: 200) and about 5 g of thecompound having a boiling point of about 127° C. was first isolated. Thestructure of this compound was confirmed by measurements such as ¹⁹F-NMRand GC-MS and the compound obtained was found to betrans-perfluoro-1-propyl-3,4-dimethylpyrrolidine (trans-PFPDMP)(molecular formula: C₉F₁₉N). The measurement data of ¹⁹F-NMR are shownin Table 1. The measurement of ¹⁹F-NMR spectrum was performed at anoperating frequency of 188.3 MHz and trifluoroacetic acid was used asthe external standard substance. The GC-MS measurement data and theelemental analysis data are shown below.

[0048] GC-MS measurement data: C₉F₁₈N⁺464 (M⁺)

[0049] Elemental analysis data (C₉F₁₉N)

[0050] Found (%): C, 22.14; F, 74.90.

[0051] Calculated (%): C, 22.36; F, 74.74.

[0052] The precision distillation was continued under the sameconditions and about 10 g of the compound having a boiling point ofabout 127.5° C. was subsequently isolated. The structure was confirmedin the same manner, and as a result, the compound was found to becis-perfluoro-1-propyl-3,4-dimethylpyrrolidine (cis-PFPDMP) (molecularformula: C₉F₁₉N). The ¹⁹F-NMR data are shown in Table 1. The GC-MSmeasurement data and the elemental analysis data are shown below. Thedata obtained were the same as those of the trans-isomer.

[0053] GC-MS measurement data: C₉F₁₈N⁺464 (M⁺)

[0054] Elemental analysis data (C₉F₁₉N)

[0055] Found (%): C, 22.18; F, 74.83.

[0056] Calculated (%): C, 22.36; F, 74.74.

[0057] The still residue solution after the distillation was introducedinto a fractional gas chromatograph (liquid phase: 20% squalane,support: chromatoron N-A (from 0.2 to 0.25 mm), length: 8 m, diameter: 9m) and by repeating the fractionation, about 8 g of the compound havinga boiling point of about 128.5° C. was isolated. The structure of thiscompound was confirmed in the same manner as above, and as a result, thecompound was found to be perfluoro-1-propyl-3-methylpiperidine (PFPMP)(molecular formula: C₉F₁₉N). The ¹⁹F-NMR data are shown in Table 1. TheGC-MS measurement data and the elemental analysis data are shown below.

[0058] GC-MS measurement data: C₉F₁₈N⁺464 (M⁺)

[0059] Elemental analysis data (C₉F₁₉N)

[0060] Found (%): C, 22.44; F, 74.80.

[0061] Calculated (%): C, 22.36; F, 74.74.

[0062] At the same time, about 10 g of the compound having a boilingpoint of about 128° C. was isolated and analyzed and this compound wasconfirmed to be perfluorotripropylamine (PFTPA) by comparing the holdingtime in the gas chromatograph, GC-MS data and the like with those of aknown compound. TABLE 1 Coupling Chemical Shift Constant Compound (ppm)(Hz)

4.9(C¹F₃) 50.4(C²F₂) 13.6(C³F^(a)) 21.0(C³F^(e)) 2.0(C⁴F^(a), C⁷F^(a))13.6(C⁴F^(e), C⁷F^(e)) 105.3(C⁵F, C⁶F) 3.8(C⁸F₃, C⁹F₃) 245 188

4.4(C¹F₃) 49.8(C²F₂) 16.2(C³F₂) 3.2(C⁴F^(a), C⁷F^(a)) 7.4(C⁴F^(e),C⁷F^(e)) 104.8(C⁵F, C⁶F) −4.0(C⁸F₃, C⁹F₃) 178

4.9(C¹F₃) 49.6(C²F₂) 12.0(C³F₂) 1.8(C⁴F^(a)) 26.0(C⁴F^(e)) 45.2(C⁵F^(a))55.9(C⁵F^(e)) 45.9(C⁶F^(a)) 63.5(C⁶F^(e)) 105.0(C⁷F) −5.7(C⁸F^(a))15.5(C⁸F^(e)) −6.7(C₉F₃) # 227 291 273 209

[0063] Respective components of the initially obtained mixed compositioncomprising four kinds of components were separated by theabove-described method, and from the analysis results on the roughcomposition (area %) by gas chromatography, each component was found tohave the name and the compositional ratio shown in Table 2.Identification of impurities other than those main components wasdifficult because they were each present in a trace amount, but it isconsidered that the impurities are mainly cyclic isomers having 9 carbonatoms. TABLE 2 Compositional Compound Ratiotrans-Perfluoro-1-propyl-3,4-dimethylpyrrolidine 13% (trans-PFPDMP)cis-Perfluoro-1-propyl-3,4-dimethylpyrrolidine (cis- 32% PFPDMP)Perfluoro-1-propyl-3-methylpiperidine (PFPMP) 24%Perfluorotripropylamine (PFTPA) 30%

Example 2

[0064] Electrolysis was performed using the same electrolytic cell inthe same manner as in Example 1, except for changing the triallylamineconcentration in the electrolytic solution and the current density. Theyield of each mixed composition obtained was examined. The results areshown in Table 3. TABLE 3 Triallylamine Concentration in ElectrolyticSolution Yield of Mixed [% by mass] Current Density [A/dm²] Composition[%] 3 to 5  1 to 2 25 5 to 10 1 to 2 25 5 to 10 2 to 4 35 5 to 10 4 to 620 15 to 20  4 to 6 15

[0065] It is seen from the results shown in Table 3 that the yield isrelatively high under the conditions such that the triallylamineconcentration is from 5 to 10% by mass and the current density is from 2to 4 A/dm².

Example 3

[0066] A triallylamine was electrolytically fluorinated under the sameconditions as in Example 1 and the purification treatment was performedthrough the same procedure to obtain a mixed composition having a purityof 99%. This composition was confirmed by gas chromatography and foundto be almost the same as the composition of Example 1.

[0067] The mixed composition obtained and perfluoropropylamine (PFTPA)separately purchased were mixed in various compositional ratios toprepare samples each in 50 ml. The samples each was charged into a 100ml-volume flask with the top being opened to air and equipped with arefluxing unit and while water cooling the refluxing unit at the top,the lower part thereof was slowly heated using a Bunsen burner to keepthe inside of the system in the refluxing state, and the temperature ofthe boiling liquid was accurately measured using a platinum resistancethermometer. The boiling data under an atmospheric pressure are shown inTable 4. TABLE 4 PFTPA Concentration in Boiling Point [° C.] MixedComposition [%] (1,010 hPa) 30 127.7 (original) 40 127.8 55 127.9 70127.9

[0068] It is seen from the measurement results shown in Table 4 that thechange in the boiling point is at most 0.2° C. and the mixed compositionis substantially a constant boiling composition over a widecompositional range under an atmospheric pressure.

Example 4

[0069] A mixed composition obtained in the same manner as in Example 1and perfluoro-1-propyl-3-methylpiperidine (PFPMP) separately isolatedand obtained were mixed in various compositional ratios to preparesamples each in 50 ml. The boiling points were measure in the samemanner as in Example 3 and the results are shown in Table 5. TABLE 5PFPMP Concentration in Boiling Point [° C.] Mixed Composition [%] (1,015hPa) 24 127.7 (original) 40 127.9 50 128 60 128

[0070] It is seen from the measurement results shown in Table 5 that thechange in the boiling point is at most 0.3° C. and the mixed compositionis substantially a constant boiling composition.

Example 5

[0071] Similar to Examples 3 and 4, a mixed composition obtained in thesame manner as in Example 1 and a mixture oftrans-perfluoro-1-propyl-3,4-dimethylpyrrolidine (trans-PFPDMP) andcis-perfluoro-1-propyl-3,4-dimethylpyrrolidine (cis-PFPDMP) separatelyisolated and obtained and in a compositional ratio of about 29%/71% weremixed in various compositional ratios to prepare samples each in 50 ml.The boiling point of each solution was measured in the same manner andthe results thereof are shown in Table 6. TABLE 6 PFPDMP Concentrationin Mixed Composition [%] Boiling Point [° C.] trans cis (1,008 hPa) 1332 127.7 17 43 127.6 20 50 127.6 23 57 127.5

[0072] It is seen from the measurement results shown in Table 6 that thechange in the boiling point is at most 0.2° C. and the mixed compositionis substantially a constant boiling composition.

Example 6

[0073] A triallylamine was electrolytically fluorinated under the sameconditions as in Example 1 and the purification treatment was performedthrough the same procedure to obtain a mixed composition having a purityof 99%. The composition was confirmed by gas chromatography and found tobe almost the same as the composition of Example 1.

[0074] 100 ml of this sample was charged into a 200 ml-volumedistillation flask and while slowly heating the lower part using aBunsen burner, the sample was distilled by the single distillation. Thetop of the flask was branched diagonally toward the lower direction andconnected to a receiver with a scale through a water-cooled condenser.The inside of the system was kept at an atmospheric pressure and theboiling point and the cumulative distillation amount (volume) wererecorded with the passage of time. The temperature was accuratelymeasured using a platinum resistance thermometer. The boiling point dataat each distillation ration (a ratio of cumulative volume of sampledistilled to the volume of sample charged) are shown in Table 7. TABLE 7Distillation Ratio [%] Boiling Point [° C.] (1,004 hPa) 20 127.8 40127.9 60 128.0 80 128.1

[0075] The change in the boiling point is about 0.3° C. during thesingle distillation under an atmospheric pressure and from this, themixed composition obtained is known to be substantially a constantboiling composition (that is, an azeotrope-like composition).

Example 7

[0076] A triallylamine was electrolytically fluorinated under the sameconditions as in Example 1 and the purification treatment was performedthrough the same procedure to obtain a mixed composition having a purityof 99%. The composition was confirmed by gas chromatography and found tobe almost the same as the composition of Example 1. Thereafter, theprecision distillation and the like were repeated to isolate respectivesamples of cis-PFPDMP, trans-PFPDMP and PFPMP.

[0077] The dielectric breakdown voltage was measured under theconditions of 25° C., an anode-cathode distance of 2.5 mm and a pressurerising rate of 3 KV/sec. The volume resistivity was measured under theconditions of 25° C., an anode-cathode distance of 1 mm and an electrodearea of 100 cm². The data obtained are shown in Table 8. The evaluationresults of the electrical insulating property are shown together inTable 8. In the evaluation, ◯ denotes excellent electrical insulatingproperty and X denotes poor electrical insulating property. TABLE 8Dielectric Volume Electrical Breakdown Resistivity Insulating SampleVoltage [kV] [Ωcm] Property Mixed composition 45  9 × 10¹⁵ ◯ (original)cis-PFPDMP 45 >1 × 10¹⁶ ◯ trans-PFPDMP 45 >1 × 10¹⁶ ◯ PFPMP 46 >1 × 10¹⁶◯

Comparative Example 1

[0078] Under the same conditions as in Example 7, PFCs having 6 or 8carbon atoms and C₄F₉C₂H₅ which is HFEs having 6 carbon atoms weremeasured on the dielectric breakdown voltage and the volume resistivity.The data are shown in Table 9. Also, the electrical insulating propertywas evaluated according to the same criteria. TABLE 9 DielectricElectrical Breakdown Voltage Volume Insulating Sample [kV] Resistivity[Ωcm] Property PFCs (C6) 39 1 × 10¹⁵ ◯ PFCs (C8) 40 8 × 10¹⁵ ◯ HFEs (C6)20 4 × 10⁸  X

[0079] The perfluorocyclicamines of the present invention and the mixedcomposition containing these perfluorocyclicamines have electricalinsulating property equal to or higher than that of conventional PFCsand HFEs. Therefore, they can be used as an electrical insulator forvarious uses.

Example 8

[0080] A triallylamine was electrolytically fluorinated under the sameconditions as in Example 1 and the purification treatment was performedthrough the same procedure to obtain a mixed composition having a purityof 99%. The composition was confirmed by gas chromatography and found tobe almost the same as the composition of Example 1.

[0081] Thereafter, precision distillation and the like were repeated toisolate samples of cis-PFPDMP, trans-PFPDMP and PFPMP. Also, PFTPA wasseparately prepared. These components were appropriately mixed toprepare five kinds in total of samples each in 50 ml.

[0082] The behavior at low temperatures was first confirmed. A vacuumDewar vessel under thorough cold insulation was designed so that astainless steel-made cylindrical container having a content volume of100 ml with a transparent acryl-made cover was fixed therein. The coverhad a propeller blade driven by an external motor by inserting it at thecenter part down to the vicinity of the bottom. Also, a slight amount ofdry nitrogen gas was always flown through the inside of the system toprevent the effect of icing due to intermixing of moisture from theoutside air.

[0083] 50 ml of the sample was charged into the stainless steel-madecontainer and placed in the Dewar vessel. The inside temperatures ofboth containers were recorded by a thermocouple thermometer for lowtemperatures. Using ethanol/dry ice as a freezing mixture, the samplewas cooled to the vicinity of −70° C. and the sample temperature wasstabilized. In order to reach a still lower temperature, a liquidnitrogen gas was supplied in place of the ethanol/dry ice through a coldinsulation piping and by controlling the amount thereof supplied, thesample temperature was stabilized in the vicinity of −100° C.

[0084] Next, the behavior at high temperatures was confirmed. Using asilicone oil bath employing a temperature controlling system by anelectrical heater in place of the vacuum Dewar vessel, the sample washeated to the vicinity of 100° C. and the sample temperature wasstabilized. Each sample was observed to examine the state of the liquidphase, the degree of fluidity and the degree of volatility at eachtemperature. The results are shown in Table 10. The results wereevaluated according to the following criteria. Each sample wasseparately measured on the boiling point and the freezing point and theresults are shown together in Table 10.

[0085] State of Liquid Phase:

[0086] ◯: transparent liquid phase was held, Δ: the phase became turbid,

[0087] X: concreted.

[0088] Fluidity:

[0089] ◯: excellent, Δ: flowable, X: not flowable

[0090] Volatility:

[0091] ◯: low, Δ: high, X: extremely high (boiled) TABLE 10 SetTemperature Freezing Boiling −100° C. −70° C. Point Point Liquid Liquid100° C. Compound [° C.] [° C.] Phase Fluidity Phase Fluidity VolatilityMixed −125 127.7 ◯ Δ ◯ ◯ ◯ Composition (original) Mixed −100 127.9 Δ X ◯Δ ◯ Composition (55% PFTPA) Mixture of −150 127.2 ◯ Δ ◯ ◯ ◯ trans/cisPFPDMP (29%/71%) cis-PFPDMP −150 127.5 ◯ Δ ◯ ◯ ◯ PFPMP −140 128.5 ◯ Δ ◯◯ ◯

Comparative Example 2

[0092] Through the same procedure as in Example 8, PFCs having 6 or 8carbon atoms and C₄F₉OC₂H₅, which is HFEs having 6 carbon atoms, wereobserved to examine the state of liquid phase, the degree of fluidityand the degree of volatility at each temperature. The results thereofare shown in Table 11. TABLE 11 Set Temperature Freezing Boiling −100°C. −70° C. Point Point Liquid Liquid 100° C. Compound [° C.] [° C.]Phase Fluidity Phase Fluidity Volatility PFCs (C6) −92 56 X X ◯ ◯ X PFCs(C8) −88 100  X X ◯ Δ X HFEs (C6) −135 77 ◯ ◯ ◯ ◯ X

[0093] The perfluorocyclicamines of the present invention and the mixedcomposition containing these perfulorocyclicamines hold the liquid phaseover a wide temperature range as compared with conventional PFCs andHFEs, and therefore, can be used as a heat medium.

[0094] According to the present invention, novel perfluorocyclicaminescan be obtained by electrolytically fluorinating a triallylamine whichis easily available. Particularly, a mixed composition thereof is aconstant boiling composition and reduced in the change of compositionduring use. Therefore, this compound is practically useful. Furthermore,the perfluorocyclicamines of the present invention have a relativelyhigh boiling point and a fairly low freezing point and therefore, notonly can hold the liquid phase over a wide temperature range but alsoexhibit excellent electrical insulating property. Accordingly, theperfluorocyclicamines can be used as an electrical insulator or a heatmedium and can replace conventional PFCs. Furthermore, by virtue of therelatively high boiling point, these substances can contribute to thereduction in the discharge of warming gases and also since chlorine atomis not contained therein, can be free from fear of rupturing the ozonelayer.

[0095] While the invention has been described in detail and withreference to specific embodiments thereof, it will be apparent to oneskilled in the art that various changes and modifications can be madetherein without departing from the spirit and scope thereof.

What is claimed is:
 1. A process for producing a perfluorocyclicamine,comprising electrolytically fluorinating a triallylamine in anhydrousliquid hydrogen fluoride to produce a perfluorocyclicamine representedby the following formula (1):

wherein —X— represents —CF(CF₃)— or —CF₂CF₂—.
 2. The process forproducing a perfluorocyclicamine as claimed in claim 1, wherein theanhydrous liquid hydrogen fluoride contains a triallylamine in an amountfrom 1 to 20% by mass.
 3. The process for producing aperfluorocyclicamine as claimed in claim 1, which compriseselectrolytically fluorinating at a current density in a range of from0.1 to 10 A/dm².
 4. The process for producing a perfluorocyclicamine asclaimed in claim 2, which comprises electrolytically fluorinating at acurrent density in a range of from 0.1 to 10 A/dm². 5.Perfluoro-1-propyl-3,4-dimethylpyrrolidine.
 6. A process for producing aconstant boiling composition comprising electrically fluorinating atriallylamine in an anhydrous liquid hydrogen fluoride, wherein saidcomposition comprises cis-perfluoro-1-propyl-3,4-dimethylpyrrolidine,trans-perfluoro-1-propyl-3,4-dimethylpyrrolidine,perfluoro-1-propyl-3-methylpiperidine and perfluorotripropylamine. 7.The process for producing a constant boiling composition as claimed inclaim 6, wherein the anhydrous liquid hydrogen fluoride contains atriallylamine in an amount of from 1 to 20% by mass.
 8. The process forproducing a constant boiling composition as claimed in claim 6, whichcomprises electrically fluorinating at a current density in a range offrom 0.1 to 10 A/dm².
 9. The process for producing a constant boilingcomposition as claimed in claim 7, which comprises electricallyfluorinating at a current density in a range of from 0.1 to 10 A/dm².10. A constant boiling composition comprisingcis-perfluoro-1-propyl-3,4-dimethylpyrrolidine,trans-perfluoro-1-propyl-3,4-dimethylpyrrolidine,perfluoro-1-propyl-3-methylpiperidine and perfluorotripropylamine. 11.The constant boiling composition as claimed in claim 10, containingperfluorotripropylamine in an amount of 55 wt % or less.
 12. Theconstant boiling composition as claimed in claim 10, wherein saidcomposition has a boiling point of from 127 to 129° C. and a freezingpoint of −100° C. or less.
 13. The constant boiling composition asclaimed in claim 11, wherein said composition has a boiling point offrom 127 to 129° C. and a freezing point of −100° C. or less.
 14. Anelectrical insulator comprising a constant boiling composition of claim10.
 15. A heat medium comprising a constant boiling composition of claim10, said composition directly or indirectly heating or cooling amaterial.
 16. The electrical insulator as claimed in claim 14, whereinsaid composition contains perfluorotripropylamine in an amount of 55 wt% or less.
 17. The electrical insulator as claimed in claim 14, whereinsaid composition has a boiling point of from 127 to 129° C. and afreezing point of −100° C. or less.
 18. The electrical insulator asclaimed in claim 16, wherein said composition has a boiling point offrom 127 to 129° C. and a freezing point of −100° C. or less.
 19. Theheat medium as claimed in claim 15, wherein said composition containsperfluorotripropylamine in an amount of 55 wt % or less.
 20. The heatmedium as claimed in claim 15, wherein said composition has a boilingpoint of from 127 to 129° C. and a freezing point of −100° C. or less.21. The heat medium as claimed in claim 19, wherein said composition hasa boiling point of from 127 to 129° C. and a freezing point of −100° C.or less.